Robin van Persie only had 20 minutes of his Manchester United debut to make his mark.

That is not enough time by anyoneís judgment, but there is a legitimate tactical question that will be posed at Sir Alex Ferguson now the Dutchman is on board.

If van Persie is to start more often than not, as will Rooney, then United will effectively be playing with a front two. Ferguson also likes his wingers, and in Nani, Ashley Young and Antonio Valencia has plenty of ammunition out wide. Then there is Shinji Kagawa, who will play best in a central position.

It is a formidable attacking line up, one which the Scot will relish being able to choose from. But his concerns will be further back, in the midfield. Against Everton United played Tom Cleverley and Paul Scholes. Fielding two players like this will ensure you get plenty of the ball, but it leaves them open to being dominated in the middle of the pitch. Rooney will drop deep but not that deep. And Kagawa can be useful for his energy there but only if either van Persie or Rooney are not playing.

Chelsea had a similar dilemma when they signed Fernando Torres. With him and Didier Drogba, they believed they had the perfect strikeforce. Yet they quickly stumbled on the problem that with two forwards who like to occupy central areas, they would have a lack of width going forward. Unlike Chelsea, United do have width. But where United have width, Chelsea had strength in central midfield. That is Unitedís weakness now.

And so the dilemma came to life against Everton, and a team who were able to use their physical strength in the middle of the pitch to bludgeon a victory against United. Itís all well and good having the best strikeforce in the league, but Fergusonís side need to control the game first. That is that much harder if you only play with two central midfielders, and neither is a proper ball winner.

It is an issue United have had for a couple of years, the lack of a real ball winner when Darren Fletcher is not available. But usually it doesnít matter because their defence is so strong. But that is another key issue. Last night United were without most of their defence, and so to some extent you can say that they were unlucky, having to play Michael Carrick and Valencia in their back four.

But on the other hand, United have it their speciality to soak up pressure and strike ruthlessly on the break. Their skill, passing ability and finishing means they do not need to win the midfield battle to win games. Just as long as their defence is in fine form, that is. When it is not, they will need a stronger midfield presence. And to do that, they may just have to sacrifice one of their forwards. That is the big question now that Ferguson will have to grapple with.